There are used various shapes of gantry of MRI apparatuses depending on the type of magnetic field used, for example, one for providing a horizontal static magnetic field space in a tunnel-shaped bore, one for providing a perpendicular static magnetic field space between upper and lower magnet units, and so forth, and in any case, examination is performed by inserting a subject into a bore (open-part) of the gantry as an static magnetic field space.
In general, tunnel type MRI apparatuses utilizing a horizontal magnetic field have a gantry shape that provides only a narrow space for inserting a subject, and therefore they have a problem that they give a confined feeling to the subject. In order to ameliorate this problem, a part of the gantry around entrance of the imaging bore opened in the front face of the gantry for inserting the subject is formed with a gently curved surface. As a typical shape of the gantry around the entrance part of the bore, there is provided a truncated cone-shaped recessing portion at the circular entrance of the imaging bore to provide a structure that the forwardly protruding frontal outer circumferential surface of the gantry is gently connected to the tunnel-shaped imaging bore via the truncated cone-shaped recessing portion.